CN113277437B

CN113277437B - Hydraulic jack

Info

Publication number: CN113277437B
Application number: CN202110573888.8A
Authority: CN
Inventors: 詹勇勇; 杜新法; 王松峰; 阮彬豪
Original assignee: T Max Hangzhou Technology Co Ltd
Current assignee: T Max Hangzhou Technology Co Ltd
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2023-03-24
Anticipated expiration: 2041-05-25
Also published as: CN113277437A

Abstract

The invention provides a hydraulic jack which comprises an outer oil cylinder (40), wherein a bearing assembly (80) for bearing or pulling a heavy object is arranged on the outer wall of the outer oil cylinder (40), the outer wall of the outer oil cylinder (40) is provided with a plurality of fixing positions, and the bearing assembly (80) can be fixed at any one of the fixing positions and can move between any two fixing positions. This hydraulic jack can adjust the position of carrier assembly on outer oil cylinder to can carry out jacking or pull the operation fast, reduce the distance of idle stroke, adaptability is better.

Description

Hydraulic jack

Technical Field

The invention relates to the field of mechanical equipment, in particular to a hydraulic jack.

Background

In the hydraulic jack in the related technology, oil in two areas in the jack are mutually converted to drive the telescopic rod to do reciprocating motion, and the function of the jack is realized through the one-way valve and the section difference. The common hydraulic jack realizes the lifting of the heavy object only by pressing down the single piston, but due to the limitation of the structure, the piston only has a lifting stroke when pressing down the heavy object, and the piston does not have a lifting stroke when being lifted. Meanwhile, the existing jack support block is fixed, and if the heavy object is too far away from the support block, the jack cannot support the heavy object or the lifting stroke is mostly wasted on the idle stroke.

Therefore, the existing hydraulic jack has technical defects on the structure and the hydraulic oil circuit system.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, an embodiment of the present invention provides a hydraulic jack, which includes an outer oil cylinder, where an outer wall of the outer oil cylinder is provided with a bearing component for bearing or pulling a heavy object, and the outer wall of the outer oil cylinder has a plurality of fixing positions, and the bearing component can be fixed at any one of the fixing positions and can move between any two of the fixing positions.

The hydraulic jack provided by the embodiment of the invention can adjust the position of the bearing component on the outer oil cylinder, so that the jacking or traction operation can be rapidly carried out, the idle stroke distance is reduced, and the adaptability is better.

According to the hydraulic jack provided by the embodiment of the invention, each fixed position is provided with a clamping groove, and the bearing component comprises: the sliding block, the bolt and the top block;

the sliding block is sleeved on the outer wall of the outer oil cylinder and can move relative to the outer oil cylinder, a bolt mounting groove is formed in the sliding block, the bolt is hinged to the bolt mounting groove, and the bolt has an opening state and a locking state and can be switched between the opening state and the locking state;

in the open state, the slide block can move relative to the outer oil cylinder;

in the locking state, part of the structure of the bolt is positioned in the bolt mounting groove, and part of the structure is positioned in the clamping groove, so that the sliding block is fixed relative to the outer oil cylinder;

the top block is arranged on the sliding block and can move along with the sliding block.

According to the hydraulic jack provided by the embodiment of the invention, the sliding block is provided with the elastic pushing assembly, the bolt is provided with the groove, and when the bolt is in the locking state, the elastic pushing assembly pushes against the groove.

According to the hydraulic jack provided by the embodiment of the invention, the elastic pushing assembly comprises a screw, a spring and a pushing bead, the slider is provided with a mounting through hole, the screw, the spring and the pushing bead are arranged in the mounting through hole, the spring is compressed between the screw and the pushing bead, and a part of the pushing bead can leak out of the end part of the mounting through hole to push against the groove.

According to the hydraulic jack provided by the embodiment of the invention, the top block is detachably connected with the sliding block, or the top block and the sliding block are integrally formed.

According to the hydraulic jack provided by the embodiment of the invention, the sliding block is provided with the insertion groove, and the insertion groove comprises the first guide part and the limiting part;

the top block is provided with an inserting part, and the inserting part comprises a second guide part and a limiting block;

the inserting part can be inserted into the inserting groove, the second guide part is matched with the first guide part, and the limiting block is matched with the limiting part.

According to the hydraulic jack provided by the embodiment of the invention, the number of the bolts is two, the slide block is provided with two bolt installation grooves, and each bolt installation groove is hinged with one bolt;

the two bolts are symmetrical about the central axis of the outer oil cylinder.

According to the hydraulic jack provided by the embodiment of the invention, the hydraulic jack further comprises an inner oil cylinder, a hydraulic cylinder body and a piston rod;

the outer oil cylinder is sleeved outside the inner oil cylinder and can move relative to the inner oil cylinder, and a reserve oil cavity is defined by the outer oil cylinder and the inner oil cylinder;

the hydraulic cylinder body is arranged in the inner oil cylinder and can move along the axial direction of the inner oil cylinder in a sealing manner, and a load oil cavity and the reserve oil cavity are respectively arranged at two ends of the hydraulic cylinder body; a piston is arranged in the hydraulic cylinder body, the piston divides the interior of the hydraulic cylinder body into a first hydraulic oil cavity and a second hydraulic oil cavity, the first hydraulic oil cavity is provided with a first oil port, and the second hydraulic oil cavity is provided with a second oil port; the first oil port and the second oil port are communicated with the load oil cavity in a one-way mode, and the first oil port and the second oil port can circulate to the load oil cavity in a one-way mode; the first oil port and the second oil port are communicated with the oil reserve cavity in a one-way mode, and the oil reserve cavity can respectively circulate to the first oil port and the second oil port in a one-way mode;

the hydraulic cylinder body is provided with an oil unloading pipeline which is communicated with the load oil cavity and the reserve oil cavity, and an oil unloading switch is arranged on the oil unloading pipeline;

the outer oil cylinder is hinged with a handle, one end of the piston rod is connected with the piston, the other end of the piston rod is connected with the handle, so that the handle can drive the piston to move in a reciprocating mode through the piston rod, the volume of the first hydraulic oil cavity and the volume of the second hydraulic oil cavity are changed, one of the first oil port and the second oil port conveys hydraulic oil to the load oil cavity, and the other oil port sucks oil from the reserve oil cavity.

According to the hydraulic jack provided by the embodiment of the invention, the outer oil cylinder is provided with the oil cylinder cover, the oil cylinder cover is hermetically arranged at the top of the outer oil cylinder, the handle is hinged to the oil cylinder cover, and the piston rod penetrates through the oil cylinder cover and is hinged to the handle.

According to the hydraulic jack provided by the embodiment of the invention, the outer oil cylinder is provided with the sleeve, the sleeve is fixedly connected to the bottom of the outer oil cylinder, and the sleeve is sleeved outside the inner oil cylinder and can slide along the outer wall of the inner oil cylinder in a sealing manner.

According to the hydraulic jack provided by the embodiment of the invention, at least part of the area of the inner wall of the sleeve is provided with the shaft sleeve, the shaft sleeve and the sleeve are coaxially arranged and are fixed relative to the sleeve, and the sleeve is sleeved on the outer wall of the inner oil cylinder and can move relative to the axial direction of the inner oil cylinder.

According to the hydraulic jack provided by the embodiment of the invention, the bottom of the inner oil cylinder is provided with the base sealing body which seals the bottom of the inner oil cylinder;

the top of the inner oil cylinder is positioned below the oil cylinder cover, and the inner cavity of the outer oil cylinder is open.

According to the hydraulic jack provided by the embodiment of the invention, the base sealing body is connected with the base, the outer wall of the inner oil cylinder is provided with the limiting component, the limiting component is used for limiting the moving range of the outer oil cylinder, and the limiting component is positioned at the upper middle position of the inner oil cylinder.

According to the hydraulic jack of the embodiment of the present invention, the hydraulic cylinder block includes: the oil way main body, the oil way upper cover and the oil way lower cover;

the outer wall of the oil path main body is in sealing contact with the inner wall of the inner oil cylinder, and the oil path main body can move axially relative to the inner oil cylinder;

a hydraulic oil cavity penetrating through the oil way main body is formed in the oil way main body, and the piston is arranged in the hydraulic oil cavity and divides the hydraulic oil cavity into the first hydraulic oil cavity and the second hydraulic oil cavity;

the oil unloading pipeline is formed on the oil way main body;

the oil path upper cover is sealed at the upper end of the hydraulic oil cavity, the oil path lower cover is sealed at the lower end of the hydraulic oil cavity, and the piston rod penetrates through the oil path upper cover and is connected with the piston.

According to the hydraulic jack provided by the embodiment of the invention, the first oil port is communicated with the oil storage cavity through a first oil inlet path and is communicated with the oil loading cavity through a first oil outlet path, the first oil inlet path is provided with a first one-way valve, and the first oil outlet path is provided with a second one-way valve;

the second oil port is communicated with the oil storage cavity through a second oil inlet path and is communicated with the oil loading cavity through a second oil outlet path, a third check valve is arranged on the second oil inlet path, and a fourth check valve is arranged on the second oil outlet path.

According to the hydraulic jack provided by the embodiment of the invention, the first oil inlet path is formed on the oil path upper cover, the first oil outlet path and the second oil inlet path are formed on the oil path main body, and the second oil outlet path is formed on the oil path lower cover.

According to the hydraulic jack provided by the embodiment of the invention, a first sinking groove is formed at the upper end of the oil way main body, a second sinking groove is formed at the lower end of the oil way main body, at least part of the structure of the oil way upper cover is arranged in the first sinking groove, and at least part of the structure of the oil way lower cover is arranged in the second sinking groove;

the inlet of the first oil outlet path is positioned in the first sinking groove, and the outlet of the second oil inlet path is positioned in the second sinking groove.

According to the hydraulic jack provided by the embodiment of the invention, the oil unloading rod is arranged in the inner oil cylinder, one end of the oil unloading rod is arranged on the oil unloading pipeline, the other end of the oil unloading rod penetrates through the oil cylinder cover and is connected with the oil unloading handle, and the oil unloading handle is hinged to the oil cylinder cover and can control the communication and the closing of the oil unloading pipeline through the oil unloading rod.

According to the hydraulic jack provided by the embodiment of the invention, a first overload protection oil path is connected between the first hydraulic oil chamber and the oil storage chamber,

and a second overload protection oil way is connected between the second hydraulic oil cavity and the oil reserve cavity.

the oil path upper cover is sealed at the upper end of the hydraulic oil cavity, and the oil path lower cover is sealed at the lower end of the hydraulic oil cavity;

the first overload protection oil way is arranged on the oil way upper cover, and the second overload protection oil way is arranged on the piston rod.

According to the hydraulic jack provided by the embodiment of the invention, the first overload protection oil circuit is provided with the first pressure one-way valve, the second overload protection oil circuit is provided with the second pressure one-way valve, the hydraulic jack is opened when the pressure difference on two sides of the first pressure one-way valve is greater than a first preset value, and the hydraulic jack is opened when the pressure difference on two sides of the second pressure one-way valve is greater than a second preset value.

According to the hydraulic jack provided by the embodiment of the invention, the piston cylinder is sleeved on the outer side of the piston rod, one end of the piston cylinder is connected with the oil cylinder cover, and the other end of the piston cylinder is connected with the hydraulic cylinder body.

According to the hydraulic jack disclosed by the embodiment of the invention, the piston rod comprises an upper piston rod and a lower piston rod which are connected with each other, the upper piston rod is connected with the handle, and the lower piston rod is connected with the piston.

Drawings

FIG. 1 is a schematic diagram of a hydraulic circuit system according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a hydraulic jack in a first cross-sectional view in accordance with an embodiment of the present invention;

FIG. 3 is an enlarged partial schematic view A of FIG. 2;

FIG. 4 is a partial cross-sectional view of a hydraulic jack in a second cross-sectional view in accordance with an embodiment of the present invention;

FIG. 5 is an enlarged partial schematic view B of FIG. 4;

FIG. 6 is a top view of the assembly of components such as the hydraulic cylinder and piston rod in one embodiment of the present invention;

FIG. 7 isbase:Sub>A schematic cross-sectional view taken along A-A of FIG. 6;

FIG. 8 is a schematic cross-sectional view taken along line B-B of FIG. 6;

fig. 9 and 10 are schematic perspective views of the oil main body at different arrangement angles according to an embodiment of the present invention;

FIG. 11 is an exploded view of the mounting of the load bearing assembly to the outer oil drum in accordance with an embodiment of the present invention;

FIGS. 12 and 13 are cross-sectional views of the mounting of the bearing assembly to the outer oil drum in accordance with one embodiment of the present invention;

FIGS. 14 and 15 illustrate the mounting of the bearing assembly on the outer barrel with the latches in different positions, respectively, in accordance with an embodiment of the present invention;

FIG. 16 is a schematic perspective view of a slider and a top block in an embodiment of the invention;

fig. 17 is a schematic view of a hydraulic jack used as a manual winch according to an embodiment of the present invention.

Reference numerals:

10-a hydraulic cylinder; 11-a first hydraulic oil chamber; 12-a second hydraulic oil chamber; 13-a piston;

111-a first oil inlet path; 112-a first oil outlet path; 113-a first one-way valve; 114-a second one-way valve; 115-first overload protection oil circuit; 1151-a first pressure check valve; 121-a second oil inlet path; 122-a second oil outlet; 123-a third one-way valve; 124-a fourth one-way valve; 125-second overload protection oil circuit; 1251-a second pressure check valve;

101-an oil passage main body; 102-oil path upper cover; 103-oil way lower cover;

1011-first sink tank; 1012-second sink tank;

20-a load oil chamber; 21-an oil discharge pipeline; 211-oil drain switch;

30-reserve oil chamber;

40-outer oil cylinder; 41-a handle; 42-oil cylinder cover; 43-a sleeve; 431-shaft sleeve; 44-a card slot;

50-inner oil cylinder; 51-a base seal; 52-a base; 53-a stop member;

60-a piston rod; 61-a piston cylinder; 62-an upper piston rod; 63-a lower piston rod;

70-oil rod unloading; 71-oil discharge handle;

80-a carrier assembly; 81-a slide block; 811-a plug pin mounting groove; 812-a resilient urging assembly; 8121-screw; 8122-spring; 8123-exopearls; 82-a latch; 821-a groove; 83-top block.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present invention and should not be construed as limiting the present invention.

Referring to fig. 1, the present embodiment provides a hydraulic oil circuit system of a hydraulic jack, which can be used to lift or pull a heavy object, depending on the purpose and method of use. The hydraulic oil circuit system mainly comprises: a hydraulic cylinder body 10, a load oil chamber 20, a reserve oil chamber 30 and an oil discharge pipeline 21;

a piston 13 is arranged in the hydraulic cylinder body 10, the piston 13 divides the interior of the hydraulic cylinder body 10 into a first hydraulic oil chamber 11 and a second hydraulic oil chamber 12, the first hydraulic oil chamber 11 is provided with a first oil port, and the second hydraulic oil chamber 12 is provided with a second oil port; the first oil port and the second oil port are communicated with the load oil cavity 20 in a one-way mode, and the first oil port and the second oil port can circulate to the load oil cavity 20 in a one-way mode; the first oil port and the second oil port are communicated with the oil reserve cavity 30 in a one-way mode, and the oil reserve cavity 30 can respectively circulate to the first oil port and the second oil port in a one-way mode; the hydraulic cylinder 10 is a double-acting hydraulic cylinder, that is, the first hydraulic oil chamber 11 and the second hydraulic oil chamber 12 are both working chambers, so that the reciprocating movement of the piston 13 can change the volumes of the first hydraulic oil chamber 11 and the second hydraulic oil chamber 12, so that one of the first oil port and the second oil port supplies hydraulic oil to the load oil chamber 20, and the other one sucks oil from the reserve oil chamber 30. Specifically, as shown in fig. 1, when the handle 41 is pressed down, the second hydraulic oil chamber 12 is compressed, hydraulic oil is pressed into the load oil chamber 20 through the fourth check valve 124, the liquid surface of the load oil chamber 20 is raised, and at the same time as this, the volume of the first hydraulic oil chamber 11 is increased, so that hydraulic oil is sucked from the reserve oil chamber 30 through the first check valve 113; when the handle 41 is lifted up, the first hydraulic oil chamber 11 is compressed, so that the hydraulic oil in the first hydraulic oil chamber 11 is pressed into the load oil chamber 20 through the second check valve 114, and the liquid level in the load oil chamber 20 is raised, and at the same time, the volume of the second hydraulic oil chamber 12 is increased, so that the hydraulic oil is sucked from the reserve oil chamber 30 through the third check valve 123; because the hydraulic cylinder body 10 is designed as a double-acting hydraulic cylinder body and is combined with the control of the unidirectional flow of an oil way, the liquid level of the load oil cavity 20 can be lifted no matter the handle 41 is pressed down or lifted up, thereby improving the working efficiency. In this embodiment, a bearing assembly 80 for supporting a weight may be disposed outside oil reserve chamber 30 and fixedly disposed with respect to oil reserve chamber 30. Bearing assembly 80 may not be separately provided and the function of supporting the weight may be achieved directly using the external structure of reserve oil chamber 30.

An oil unloading pipeline 21 is also arranged in the embodiment, and the oil unloading pipeline 21 is communicated with the load oil cavity 20 and the reserve oil cavity 30; after the hydraulic oil circuit system is lifted or the traction work is finished, the hydraulic oil in the load oil cavity 20 can flow into the reserve oil cavity 30 through the oil unloading pipeline 21.

In one embodiment, the first oil port is communicated with the oil reserve chamber 30 through a first oil inlet passage 111, and is communicated with the load oil chamber 20 through a first oil outlet passage 112, a first check valve 113 is disposed on the first oil inlet passage 111, and a second check valve 114 is disposed on the first oil outlet passage 112; the second port is communicated with the reserve oil chamber 30 through a second oil inlet path 121, and is communicated with the load oil chamber 20 through a second oil outlet path 122, a third check valve 123 is disposed on the second oil inlet path 121, and a fourth check valve 124 is disposed on the second oil outlet path 122. Thereby, the one-way communication of the first and second oil ports with the load oil chamber 20 and the one-way communication of the first and second oil ports with the reserve oil chamber 30 are achieved. In addition to this embodiment, there are other embodiments that can achieve one-way communication of the first and second oil ports with the load oil chamber 20 and one-way communication of the first and second oil ports with the reserve oil chamber 30.

In one embodiment, a first overload protection oil passage 115 is connected between the first hydraulic oil chamber 11 and the oil reserve chamber 30, and a second overload protection oil passage 125 is connected between the second hydraulic oil chamber 12 and the oil reserve chamber 30. When the pressure in the first hydraulic oil chamber 11 is greater than the preset value, the first overload protection oil path 115 opens to release pressure to the reserve oil chamber 30, thereby preventing damage to the hydraulic cylinder block 10, and similarly, when the pressure in the second hydraulic oil chamber 12 is greater than the preset value, the second overload protection oil path 125 opens to release pressure to the reserve oil chamber 30, thereby preventing damage to the hydraulic cylinder block 10. Specifically, a first pressure check valve 1151 may be provided in the first overload protection oil passage 115, and a second pressure check valve 1251 may be provided in the second overload protection oil passage 125. The first and second

pressure check valves

1151 and 1251 are both openable at a predetermined pressure, which may or may not be the same.

Referring to fig. 11 to 15, there is further provided in this embodiment a hydraulic jack including an outer oil cylinder 40, wherein an outer wall of the outer oil cylinder 40 is provided with a bearing assembly 80 for bearing or pulling a heavy object, the outer wall of the outer oil cylinder 40 has a plurality of fixing positions, and the bearing assembly 80 can be fixed at any one of the fixing positions and can move between any two of the fixing positions. When the hydraulic jack is used, if the position of the bearing component 80 is far away from the lifted surface, the fixing position of the bearing component 80 can be adjusted first, so that the bearing component 80 is fixed at the position which is nearest to the lifted surface. Then, the lifting work is performed, thereby reducing the dead stroke.

Specifically, each fixed position has all seted up draw-in groove 44, and carrier assembly 80 includes: a slide block 81, a latch 82, and a top block 83; the sliding block 81 is sleeved on the outer wall of the outer oil cylinder 40 and can move relative to the outer oil cylinder 40, a plug pin installation groove 811 is formed in the sliding block 81, one end of the plug pin 82 is hinged to the plug pin installation groove 811 through a hinge shaft 84, and the plug pin 82 has an opening state (shown in fig. 15) and a locking state (shown in fig. 14) and can be switched between the opening state and the locking state; in the open state, the slider 81 is movable relative to the outer oil cylinder 40; in the locked state, a portion of the latch 82 is disposed in the latch mounting groove 811 and a portion of the latch is disposed in the catch groove 44 to secure the slider 81 relative to the outer oil drum 40.

In one embodiment, the latch 82 rotates into the latch mounting groove 811 in the locked state and rotates one end of the latch 82 out of the latch mounting groove 811 in the open state.

Wherein, the top block 83 is installed on the sliding block 81 and can move synchronously with the sliding block 81. The top block 83 is detachably connected with the sliding block 81. The concrete connection mode can be splicing, clamping, mortise and tenon connection, threaded connection and the like.

Referring to fig. 16, the sliding block 81 is provided with an insertion groove 813, and the insertion groove 813 includes a first guide portion 8131 and a limiting portion 8132; the top block 83 has an inserting portion 831, the inserting portion 831 includes a second guide portion 8311 and a limiting block 8312, the inserting portion 831 can be inserted into the inserting groove 813, the second guide portion 8311 is matched with the first guide portion 8131, and the limiting block 8312 is matched with the limiting portion 8132. The plug structure enables the sliding block 81 and the top block 83 to be quickly connected and quickly detached, and the stability after connection is high. The matching surfaces of the first guide part 8131 and the second guide part 8311 are both curved surfaces.

In one embodiment, the sliding block 81 is provided with an elastic pushing assembly 812, the pin 82 is provided with a groove 821, and when the pin 82 is in the locking state, the elastic pushing assembly 812 pushes the groove 821, as shown in fig. 12 and 13, the elastic pushing assembly 812 pushes the groove 821 to limit the pin 82 to rotate, and the elastic pushing assembly 812 limits the pin 82 to prevent the pin 82 from rotating arbitrarily, and applies a certain external force to the pin 82 to enable the groove 821 to be separated from the limit of the elastic pushing assembly 812, so as to switch from the locking state to the opening state.

Further, the elastic pushing assembly 812 includes a screw 8121, a spring 8122 and a top bead 8123, the slider 81 is provided with a mounting through hole, the screw 8121, the spring 8122 and the top bead 8123 are disposed in the mounting through hole, the spring 8122 is compressed between the screw 8121 and the top bead 8123, and a portion of the top bead 8123 can leak out from an end of the mounting through hole to push against the groove 821. As shown in fig. 14, the latch 82 is positioned in the latch fitting groove 811, at which time the position of the slider 81 is fixed; as shown in fig. 15, one end of the insert pin 82 is rotated out of the insert pin fitting groove 811, and at this time, the position of the slider 81 can be adjusted up and down.

As shown in fig. 13, the top block 83 is detachably connected to the slider 81. The structure of the top block 83 can be in various forms, the lifting surface of the top block 83 is provided with anti-slip stripes, and the lifting surface of the top block 83 can be perpendicular to the lifting direction of the outer oil cylinder 40 (i.e. horizontally arranged as shown in the figure) or can be arranged as an inclined surface so as to use a special working environment. Thus, the top block 83 and the sliding block 81 are detachably connected, so that the top block 83 of different types can be replaced conveniently. The top block 83 and the sliding block 81 may be integrally formed.

In one embodiment, the number of the pins 82 is two, the sliding block 81 is provided with two pin mounting grooves 811, and each pin mounting groove 811 is hinged with one pin 82; the two latches 82 are symmetrical about the central axis of the outer oil drum 40. By such arrangement, the connection between the sliding block 81 and the outer oil cylinder 40 can be firmer and more stable.

Referring to fig. 2-5, the internal construction of the hydraulic jack is described, and in one embodiment, the hydraulic jack includes: the inner oil tube 50, the hydraulic cylinder body 10 and the piston rod 60,

wherein, the outer oil cylinder 40 is provided with a handle 41; the outer oil cylinder 40 is sleeved outside the inner oil cylinder 50 and can move relative to the inner oil cylinder 50, and the outer oil cylinder 40 and the inner oil cylinder 50 define the reserve oil cavity 30; the reserve oil chamber 30 may be inside the inner oil cylinder 50, may be between the outer oil cylinder 40 and the inner oil cylinder 50, or may be both inside the inner oil cylinder 50 and between the outer oil cylinder 40 and the inner oil cylinder 50.

The hydraulic cylinder body 10 is arranged in the inner oil cylinder 50 and can move along the axial direction of the inner oil cylinder 50 in a sealing manner, and a load oil cavity 20 and a reserve oil cavity 30 are respectively arranged at two ends of the hydraulic cylinder body 10; a piston 13 is arranged in the hydraulic cylinder body 10, the piston 13 divides the interior of the hydraulic cylinder body 10 into a first hydraulic oil chamber 11 and a second hydraulic oil chamber 12, the first hydraulic oil chamber 11 is provided with a first oil port, and the second hydraulic oil chamber 12 is provided with a second oil port; the first oil port and the second oil port are communicated with the load oil cavity 20 in a one-way mode, and the first oil port and the second oil port can circulate to the load oil cavity 20 in a one-way mode; the first oil port and the second oil port are communicated with the oil reserve cavity 30 in a one-way mode, and the oil reserve cavity 30 can respectively circulate to the first oil port and the second oil port in a one-way mode;

the hydraulic cylinder body 10 is provided with an oil unloading pipeline 21, the oil unloading pipeline 21 is communicated with the load oil cavity 20 and the reserve oil cavity 30, and an oil unloading switch 211 is arranged on the oil unloading pipeline 21; the oil discharge switch 211 can control the on-off of the oil discharge pipeline 21.

One end of the piston rod 60 is connected to the piston 13, and the other end is connected to the handle 41, so that the handle 41 can drive the piston 13 to reciprocate through the piston rod 60 to change the volumes of the first hydraulic oil chamber 11 and the second hydraulic oil chamber 12, so that one of the first oil port and the second oil port can deliver hydraulic oil to the load oil chamber 20, and the other can suck oil from the reserve oil chamber 30.

In the above embodiment, the piston rod 60 also plays a certain supporting role, when the hydraulic oil in the load oil chamber 20 increases, the hydraulic cylinder body 10 is pushed to move upwards, and the supporting force is transmitted to the handle 41 through the piston rod 60 and further transmitted to the outer oil cylinder 40, so that the hydraulic cylinder body 10, the outer oil cylinder 40 and the piston rod 60 move upwards relative to the inner oil cylinder 50 synchronously, thereby realizing the function of jacking or traction.

In one embodiment, the outer oil cylinder 40 is provided with an oil cylinder cover 42, the oil cylinder cover 42 is hermetically arranged at the top of the outer oil cylinder 40, the handle 41 is hinged to the oil cylinder cover 42, and the piston rod 60 is hinged to the handle 41 through the oil cylinder cover 42. That is, in this embodiment, the top of the outer oil cylinder 40 is sealed by the oil cylinder cover 42, and the oil cylinder cover 42 also functions as the mounting handle 41.

Referring to fig. 3 and 5, the outer oil cylinder 40 is provided with a sleeve 43, the sleeve 43 is fixedly connected to the bottom of the outer oil cylinder 40, and the sleeve 43 is sleeved outside the inner oil cylinder 50 and can slide along the outer wall of the inner oil cylinder 50 in a sealing manner. The sleeve 43 can play a role in sealing the bottom of the outer oil cylinder 40 and also play a role in guiding, so that the coaxiality of the outer oil cylinder 40 and the inner oil cylinder 50 is ensured, and the outer oil cylinder 40 is prevented from being inclined in the ascending process.

Further, at least a partial region of the inner wall of the sleeve 43 is provided with a boss 431, the boss 431 is provided coaxially with the sleeve 43 and fixed relative to the sleeve 43, and the sleeve 43 is fitted over the outer wall of the inner oil tube 50 and is movable relative to the inner oil tube 50 in the axial direction. The sleeve 431 also serves as a guide, and a plurality of the sleeves 431 may be provided, as shown in fig. 3, one sleeve 431 is provided at each of the upper and lower ends of the sleeve 43.

In one embodiment, the bottom of the inner oil cylinder 50 is provided with a base sealing body 51, and the base sealing body 51 seals the bottom of the inner oil cylinder 50; the top of the inner oil drum 50 is located below the oil drum cover 42 and is open in the inner cavity of the outer oil drum 40. Thereby communicating the inner cavity of the inner oil cylinder 50 with the inner cavity of the outer oil cylinder 40, and the reserve oil cavity 30 is formed in the inner cavity of the oil cylinder 50 and the inner cavity of the outer oil cylinder 40. The bottom of the internal oil cylinder 50 may not be provided with the base sealing body 51, but the bottom of the internal oil cylinder 50 may be directly designed to be of a sealed structure, that is, the internal oil cylinder 50 may be a cylinder with only one upper opening. When the inner oil cylinder 50 is designed to have two openings, a base seal body 51 is provided at the bottom of the inner oil cylinder 50 for sealing.

The base sealing body 51 may also be a support base for the hydraulic jack, and a larger support surface may be designed. One base 52 may also be specially designed. For example, the base seal body 51 is connected to the base 52, and the base 52 and the base seal body 51 are detachably connected. The base 52 can be removed for use if necessary.

In one embodiment, referring to fig. 2, the outer wall of the inner oil cylinder 50 is provided with a limiting part 53, the limiting part 53 is used for limiting the moving range of the outer oil cylinder 40, the limiting part 53 is located at a position above the middle part of the inner oil cylinder 50, and the limiting part 53 is fixed relative to the inner oil cylinder 50.

Referring to fig. 3, 5-8, in one embodiment, the hydraulic cylinder block 10 basically includes: an oil passage main body 101, an oil passage upper cover 102, and an oil passage lower cover 103; the outer wall of the oil passage main body 101 is in sealing contact with the inner wall of the inner oil cylinder 50, and the oil passage main body 101 can move relative to the inner oil cylinder 50 in the axial direction; a hydraulic oil chamber penetrating through the oil path main body 101 is formed in the oil path main body 101, and the piston 13 is arranged in the hydraulic oil chamber and divides the hydraulic oil chamber into a first hydraulic oil chamber 11 and a second hydraulic oil chamber 12; an oil path upper cover 102 is sealed at the upper end of the hydraulic oil cavity, an oil path lower cover 103 is sealed at the lower end of the hydraulic oil cavity, a piston rod 60 passes through the oil path upper cover 102 to be connected with a piston 13, and an oil unloading path 21 is formed in an oil path main body 101. The hydraulic principle of the hydraulic jack of the present embodiment can refer to fig. 1 and the description about the hydraulic oil circuit system in the present embodiment.

In one embodiment, referring to fig. 7-8, the first oil port is communicated with the reserve oil chamber 30 through a first oil inlet path 111, and is communicated with the load oil chamber 20 through a first oil outlet path 112, a first check valve 113 is disposed on the first oil inlet path 111, and a second check valve 114 is disposed on the first oil outlet path 112; the second port is communicated with the reserve oil chamber 30 through a second oil inlet path 121, and is communicated with the load oil chamber 20 through a second oil outlet path 122, a third check valve 123 is disposed on the second oil inlet path 121, and a fourth check valve 124 is disposed on the second oil outlet path 122.

The first oil inlet passage 111 is formed in the oil passage upper cover 102, the first oil outlet passage 112 and the second oil inlet passage 121 are formed in the oil passage main body 101, and the second oil outlet passage 122 is formed in the oil passage lower cover 103.

In one embodiment, referring to fig. 9 and 10, a first sinking groove 1011 is formed at the upper end of the oil main body 101, a second sinking groove 1012 is formed at the lower end of the oil main body 101, at least part of the oil upper cover 102 is disposed in the first sinking groove 1011, and at least part of the oil lower cover 103 is disposed in the second sinking groove 1012; the inlet of the first oil outlet passage 112 is located in the first sink groove 1011, and the outlet of the second oil inlet passage 121 is located in the second sink groove 1012.

Referring to fig. 7 and 8, a certain gap may be formed between the top of the oil passage lower cover 103 and the bottom of the second sunken groove 1012, so that the hydraulic oil at the outlet of the second oil inlet passage 121 may rapidly flow into the second hydraulic oil chamber 12, and if no gap is provided, a flow channel groove may be formed at the top of the oil passage lower cover 103; similarly, a certain gap may be provided between the bottom of the oil path upper cover 102 and the bottom of the first sinking groove 1011, so that the hydraulic oil in the first hydraulic oil chamber 11 enters the inlet of the first oil outlet path 112, and a runner groove may be provided at the bottom of the oil path upper cover 102 if no gap is provided.

In one embodiment, referring to fig. 2 and 8, an oil unloading rod 70 is disposed in the inner oil cylinder 50, one end of the oil unloading rod 70 is disposed in the oil unloading pipeline 21, the other end of the oil unloading rod 70 passes through the oil cylinder cover 42 and is connected to an oil unloading handle 71, the oil unloading handle 71 is hinged to the oil cylinder cover 42, and the oil unloading rod 70 can control the connection and the disconnection of the oil unloading pipeline 21. Specifically, a return spring (not shown in the figure) may be disposed on the oil discharging rod 70, when the oil discharging rod 70 is pressed downward, the bottom of the oil discharging line 21 is opened, so as to communicate the oil storage chamber 30 and the load oil chamber 20, thereby realizing oil discharging and pressure relief of the load oil chamber 20, and when the oil discharging rod 70 is stopped being pressed, the oil discharging rod 70 automatically closes the oil discharging line 21 under the action of the return spring.

pressure check valves

1151 and 1251 are both openable at a predetermined pressure, which may be the same or different.

The first overload protection oil path 115 is disposed on the oil path upper cover 102, and the second overload protection oil path 125 is disposed on the piston rod 60. At least a partial area of the piston rod 60 is provided with a hollow structure, and the bottom end of the piston 13 has an opening so that the hydraulic oil of the second hydraulic oil chamber 12 can flow into the hollow piston rod 60 through the opening and then to the position of the second pressure check valve 1251, and the outlet of the second pressure check valve 1251 is provided to communicate with the oil reservoir chamber 30.

In one embodiment, the first overload protection oil path 115 is provided with a first pressure check valve 1151, the second overload protection oil path 125 is provided with a second pressure check valve 1251, the first pressure check valve 1151 opens when the pressure difference between two sides is greater than a first preset value, and the second pressure check valve 1251 opens when the pressure difference between two sides is greater than a second preset value. The opening pressure value of the first pressure check valve 1151 and the opening pressure value of the second pressure check valve 1251 may be the same or different.

In one embodiment, a piston cylinder 61 is sleeved outside the piston rod 60, and one end of the piston cylinder 61 is connected to the cylinder cover 42 and the other end is connected to the hydraulic cylinder 10. The piston cylinder 61 serves as a support between the hydraulic cylinder 10 and the oil cylinder cover 42, and the hydraulic cylinder 10 moving upward transmits a support force to the oil cylinder cover 42 through the piston cylinder 61, and when the piston cylinder 61 supports the oil cylinder cover 42, the support force of the piston rod 60 to the oil cylinder cover 42 is reduced or no support force. The arrangement can reduce damage to the piston rod 60 and prolong the service life of the hydraulic jack.

In one embodiment, the piston rod 60 includes an upper piston rod 62 and a lower piston rod 63 connected to each other, the upper piston rod 62 being connected to the handle 41, and the lower piston rod 63 being connected to the piston 13. Wherein, a hollow structure is provided in the lower piston rod 63, and a second pressure check valve 1251 is provided therein, and one or more through holes may be opened on the piston cylinder 61 to communicate the hydraulic oil in the piston cylinder 61 with the reserve oil chamber 30.

The hydraulic jack of this embodiment still has manual capstan winch function, and concrete usage is as follows: referring to fig. 17, the fiber rope 5 passes through the base accessory 3, the base 52 and the towing accessory 4 (to prevent the fiber rope from turning over when stressed), one end of the fiber rope 5 is connected with a fixed object, and the other end is connected with the hydraulic jack base 52; one end of the drag chain 2 is connected with the drag object 1, the other end of the drag chain is fixed on the drag accessory 4 of the hydraulic jack, the push-pull handle 41 realizes the drag of the drag object 1, the drag chain 2 is alternatively hooked through the hook on the base accessory 3 and the hook on the drag accessory 4, so that the drag object 1 can not slide to the initial position when the hydraulic jack reciprocates, and the function of the manual winch is realized.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the second feature or the first and second features may be indirectly contacting each other through intervening media. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. The hydraulic jack is characterized by comprising an outer oil cylinder (40), wherein the outer wall of the outer oil cylinder (40) is provided with a bearing component (80) for bearing or pulling a heavy object, the outer wall of the outer oil cylinder (40) is provided with a plurality of fixing positions, and the bearing component (80) can be fixed at any one of the fixing positions and can move between any two fixing positions;

the hydraulic jack also comprises an inner oil cylinder (50), a hydraulic cylinder body (10) and a piston rod (60);

the outer oil cylinder (40) is sleeved outside the inner oil cylinder (50) and can move relative to the inner oil cylinder (50), and the outer oil cylinder (40) and the inner oil cylinder (50) define a reserve oil cavity (30);

the hydraulic cylinder body (10) is arranged in the inner oil cylinder (50) and can move along the axial direction of the inner oil cylinder (50) in a sealing manner, and a load oil cavity (20) and a reserve oil cavity (30) are respectively arranged at two ends of the hydraulic cylinder body (10); a piston (13) is arranged in the hydraulic cylinder body (10), the piston (13) divides the interior of the hydraulic cylinder body (10) into a first hydraulic oil chamber (11) and a second hydraulic oil chamber (12), the first hydraulic oil chamber (11) is provided with a first oil port, and the second hydraulic oil chamber (12) is provided with a second oil port; the first oil port and the second oil port are communicated with the load oil cavity (20) in a one-way mode, and the first oil port and the second oil port can flow to the load oil cavity (20) in a one-way mode; the first oil port and the second oil port are communicated with the oil reserve cavity (30) in a one-way mode, and the oil reserve cavity (30) can respectively circulate to the first oil port and the second oil port in a one-way mode;

the hydraulic cylinder body (10) is provided with an oil unloading pipeline (21), the oil unloading pipeline (21) is communicated with the load oil cavity (20) and the oil storage cavity (30), and an oil unloading switch is arranged on the oil unloading pipeline (21);

a handle (41) is hinged to the outer oil cylinder (40), one end of the piston rod (60) is connected with the piston (13), and the other end of the piston rod is connected with the handle (41), so that the handle (41) can drive the piston (13) to move back and forth through the piston rod (60) to change the volumes of the first hydraulic oil chamber (11) and the second hydraulic oil chamber (12), and one of the first oil port and the second oil port conveys hydraulic oil to the load oil chamber (20), and the other oil port sucks oil from the reserve oil chamber (30);

the outer oil cylinder (40) is provided with an oil cylinder cover (42), the oil cylinder cover (42) is arranged at the top of the outer oil cylinder (40) in a sealing mode, the handle (41) is hinged to the oil cylinder cover (42), and the piston rod (60) penetrates through the oil cylinder cover (42) and is hinged to the handle (41).

2. The hydraulic jack of claim 1, wherein each of the securing locations is provided with a catch (44), the carrier assembly (80) comprising: a sliding block (81), a bolt (82) and a top block (83);

the sliding block (81) is sleeved on the outer wall of the outer oil cylinder (40) and can move relative to the outer oil cylinder (40), a bolt mounting groove (811) is formed in the sliding block (81), the bolt (82) is hinged to the bolt mounting groove (811), and the bolt (82) has an opening state and a locking state and can be switched between the opening state and the locking state;

in the open state, the slider (81) is movable relative to the outer oil cylinder (40);

in the locking state, part of the structure of the bolt (82) is positioned in the bolt mounting groove (811), and part of the structure is positioned in the clamping groove (44), so that the sliding block (81) is fixed relative to the outer oil cylinder (40);

the top block (83) is mounted on the sliding block (81) and can move along with the sliding block (81).

3. The hydraulic jack according to claim 2, wherein the sliding block (81) is provided with an elastic pushing assembly (812), the bolt (82) is provided with a groove (821), and when the bolt (82) is in the locking state, the elastic pushing assembly (812) pushes against the groove (821).

4. The hydraulic jack of claim 3, wherein the elastic pushing assembly (812) comprises a screw (8121), a spring (8122) and a top bead (8123), a mounting through hole is formed in the sliding block (81), the screw (8121), the spring (8122) and the top bead (8123) are arranged in the mounting through hole, the spring (8122) is compressed between the screw (8121) and the top bead (8123), and a part of the top bead (8123) can leak out from the end of the mounting through hole to be pushed against the groove (821).

5. A hydraulic jack as claimed in claim 2, characterised in that the top block (83) is detachably connected to the slide (81) or in that the top block (83) is integrally formed with the slide (81).

6. The hydraulic jack of claim 5, wherein the sliding block (81) is provided with an insertion groove (813), and the insertion groove (813) comprises a first guide part (8131) and a limiting part (8132);

the top block (83) is provided with an inserting part (831), and the inserting part (831) comprises a second guide part (8311) and a limiting block (8312);

the inserting part (831) can be inserted into the inserting groove (813), the second guide part (8311) is matched with the first guide part (8131), and the limiting block (8312) is matched with the limiting part (8132).

7. The hydraulic jack as claimed in claim 2, wherein the number of the pins (82) is two, the sliding block (81) is provided with two pin mounting grooves (811), and each pin mounting groove (811) is hinged to one pin (82);

the two bolts (82) are symmetrical about the central axis of the outer oil cylinder (40).

8. The hydraulic jack of claim 1, wherein the outer oil cylinder (40) is provided with a sleeve (43), the sleeve (43) is fixedly connected to the bottom of the outer oil cylinder (40), and the sleeve (43) is sleeved outside the inner oil cylinder (50) and can slide along the outer wall of the inner oil cylinder (50) in a sealing manner.

9. The hydraulic jack according to claim 8, characterized in that at least a partial region of the inner wall of the sleeve (43) is provided with a bushing (431), the bushing (431) is coaxially arranged with the sleeve (43) and fixed relative to the sleeve (43), and the sleeve (43) is sleeved on the outer wall of the inner oil cylinder (50) and can move axially relative to the inner oil cylinder (50).

10. The hydraulic jack according to claim 1, characterized in that a base seal body (51) is provided to the bottom of the inner oil cylinder (50), the base seal body (51) sealing the bottom of the inner oil cylinder (50);

the top of the inner oil cylinder (50) is positioned below the oil cylinder cover (42) and is opened in the inner cavity of the outer oil cylinder (40).

11. The hydraulic jack of claim 10, wherein the base sealing body (51) is connected with a base (52), the outer wall of the inner oil cylinder (50) is provided with a limiting part (53), the limiting part (53) is used for limiting the moving range of the outer oil cylinder (40), and the limiting part (53) is positioned on the upper middle part of the inner oil cylinder (50).

12. Hydraulic jack according to claim 1, characterized in that the hydraulic cylinder (10) comprises: an oil path main body (101), an oil path upper cover (102) and an oil path lower cover (103);

the outer wall of the oil path main body (101) is in sealing contact with the inner wall of the inner oil cylinder (50), and the oil path main body (101) can move in the axial direction relative to the inner oil cylinder (50);

a hydraulic oil cavity penetrating through the oil way main body (101) is formed in the oil way main body (101), and the piston (13) is arranged in the hydraulic oil cavity and divides the hydraulic oil cavity into the first hydraulic oil cavity (11) and the second hydraulic oil cavity (12);

the oil discharge line (21) is formed in the oil line main body (101);

the oil path upper cover (102) is sealed at the upper end of the hydraulic oil cavity, the oil path lower cover (103) is sealed at the lower end of the hydraulic oil cavity, and the piston rod (60) penetrates through the oil path upper cover (102) to be connected with the piston (13).

13. The hydraulic jack of claim 12, wherein the first oil port communicates with the reserve oil chamber (30) through a first oil inlet passage (111) and communicates with the load oil chamber (20) through a first oil outlet passage (112), the first oil inlet passage (111) is provided with a first check valve (113), and the first oil outlet passage (112) is provided with a second check valve (114);

the second oil port is communicated with the oil storage cavity (30) through a second oil inlet path (121) and communicated with the load oil cavity (20) through a second oil outlet path (122), a third check valve (123) is arranged on the second oil inlet path (121), and a fourth check valve (124) is arranged on the second oil outlet path (122).

14. The hydraulic jack according to claim 13, wherein the first oil inlet passage (111) is formed in the oil passage upper cover (102), the first oil outlet passage (112) and the second oil inlet passage (121) are formed in the oil passage main body (101), and the second oil outlet passage (122) is formed in the oil passage lower cover (103).

15. The hydraulic jack of claim 14, wherein a first sinking groove (1011) is formed at the upper end of the oil main body (101), a second sinking groove (1012) is formed at the lower end of the oil main body (101), at least a part of the structure of the oil upper cover (102) is arranged in the first sinking groove (1011), and at least a part of the structure of the oil lower cover (103) is arranged in the second sinking groove (1012);

the inlet of the first oil outlet path (112) is positioned in the first sinking groove (1011), and the outlet of the second oil inlet path (121) is positioned in the second sinking groove (1012).

16. The hydraulic jack of claim 1, wherein an oil unloading rod (70) is arranged in the inner oil cylinder (50), one end of the oil unloading rod (70) is arranged on the oil unloading pipeline (21), the other end of the oil unloading rod penetrates through the oil cylinder cover (42) and is connected with an oil unloading handle (71), and the oil unloading handle (71) is hinged to the oil cylinder cover (42) and can control the communication and the closing of the oil unloading pipeline (21) through the oil unloading rod (70).

17. The hydraulic jack according to claim 1, wherein a first overload protection oil path (115) is connected between the first hydraulic oil chamber (11) and the reserve oil chamber (30),

and a second overload protection oil way (125) is connected between the second hydraulic oil chamber (12) and the oil storage chamber (30).

18. Hydraulic jack according to claim 17, characterized in that the hydraulic cylinder (10) comprises: an oil path main body (101), an oil path upper cover (102) and an oil path lower cover (103);

the outer wall of the oil path main body (101) is in sealing contact with the inner wall of the inner oil cylinder (50), and the oil path main body (101) can move in the axial direction of the inner oil cylinder (50);

the oil path upper cover (102) is sealed at the upper end of the hydraulic oil cavity, and the oil path lower cover (103) is sealed at the lower end of the hydraulic oil cavity;

the first overload protection oil path (115) is arranged on the oil path upper cover (102), and the second overload protection oil path (125) is arranged on the piston rod (60).

19. The hydraulic jack of claim 18, wherein a first pressure check valve (1151) is arranged on the first overload protection oil path (115), a second pressure check valve (1251) is arranged on the second overload protection oil path (125), the first pressure check valve (1151) is opened when the pressure difference between two sides is greater than a first preset value, and the second pressure check valve (1251) is opened when the pressure difference between two sides is greater than a second preset value.

20. The hydraulic jack of claim 1, wherein a piston cylinder (61) is sleeved on the outer side of the piston rod (60), one end of the piston cylinder (61) is connected with the oil cylinder cover (42), and the other end of the piston cylinder is connected with the hydraulic cylinder body (10).

21. The hydraulic jack of claim 1, wherein the piston rod (60) includes an upper piston rod (62) and a lower piston rod (63) connected to each other, the upper piston rod (62) being connected to the handle (41), the lower piston rod (63) being connected to the piston (13).